Field of the Invention
The invention pertains to a transmitter and/or receiver unit for an antitheft system of a motor vehicle. The unit has a printed circuit board carrying an electronic circuit and a plug-type connector with electrical contact elements which are electrically connected, at their printed circuit board ends, to the circuit via conductor tracks of the printed circuit board.
Commonly assigned U.S. Pat. No. 5,844,524 (German patent No. DE 196 14 362 C1) describes a transmitter and receiver unit with a circuit on a printed circuit board. An associated antenna is embodied in the form of conductor tracks both on the upper side and on the underside of a printed circuit board. The printed circuit board has, along the conductor tracks, through-plated holes through which the conductor tracks on the upper side are electrically connected to those on the lower side. The effective radiant surface of the antenna is thus increased.
The attachment of the printed circuit board, for example by clamping mounts in the region of the conductor tracks, can result in the conductor tracks of such an antenna being mechanically eroded in the course of time owing to shaking stresses by the mounts resting on the printed circuit board. The conductor tracks are then abraded and the antenna is then no longer effective, or can be used only to a limited degree, owing to its shortened electrical length. Furthermore, the antennas on the printed circuit board take up a very large amount of space. The printed circuit board layout has to be adapted to the antenna. In particular, electromagnetic compatibility has to be allowed for.
Japanese patent abstract JP 08222924 A discloses a plug-type connector which has a contact element that is not connected to other elements (an idle terminal). That contact element is used as a receiving antenna. However, the plug-type connector does not have any additional parts of an antenna.